The invention is directed to a guidance device for a laser beam repeatedly reflected at 45.degree. mirrors for three-dimensional machining of workpieces, with five controlled axes of motion, of which the first and second axes of motion are the horizontal coordinate axes X and Y, the third and fourth axes of motion are realized coaxially in a rotatable telescopic installation which is variable as to length or such like and the fourth axis of motion is a horizontal swiveling axis, around which the laser head can be swiveled, whereby beginning with the third axis of motion a self-supporting design is provided. By self-supporting design a device is meant, in which the components causing the motion and the components guiding the laser beam are not designed separately from each other and then are connected with each other side by side, rather they are combined into a homogeneous design centrally guiding the laser beam.
Such guidance devices are utilized in laser cutting installations for material which can be cut by laser and which have a thickness cuttable by a laser and they permit, because of their five degrees of freedom as far as motion is concerned, the application of cuts and penetrations also in case of three-dimensional workpieces.
A known laser cutting device of this species (DE-PS No. 30 11 244) enables laser cuts of three-dimensional hollow and possibly flexible molded parts, which for this purpose are applied in a positively locking manner upon the support mold which complements the molded part.
If this known device has to perform cuts in workpiece areas arranged at an angle with respect to the horizontal, the laser head is adjusted at the desired angle with respect to the surface of the workpiece area concerned. In the interest of a uniform gap width of the cutting gaps with as high a feed velocity or cutting output as possible the laser head is appropriately adjusted perpendicularly to the workpiece surface. In any case hereby the laser head is pivoted around its horizontal swivelling axis, whereby the point of impact, meaning the point where the laser beam impinges upon the workpiece surface, lies outside of the vertical axis of the telescopic device. But also with a vertical adjustment of the laser head its central axis lies offset to the axis of the telescopic installation because of the required two-time beam reflection at the laser head swiveling axis, whereby also in the simplest vertical application case of the guidance device the point of impingement lies outside of the telescopic axis.
This location of the point of impingement complicates the preparation of a program for the computer controlled movement of the laser head and its guidance device to a considerable degree. Over and above that the guidance device is obliged, because it moves outside the workpiece, meaning externally of the cutting gap, to cover considerable travel distances and at contour transitions at the workpiece, for instance when the point of impingement passes out of a straight line into a curved movement path, it has to be moved with varying velocities, in order for the feed at the cutting point to remain as constant as possible in view of the desired uniform cutting gap width.
If penetrations in horizontal and/or non horizontal workpiece areas have to be cut with the known device, then the guidance device must be moved in the X- and Y movement areas in case of horizontally oriented penetrations and in case of non-horizontally oriented penetrations it must be additionally moved in the vertical Z-axis of motion, if a specific laser impingement angle upon the workpiece surface is to be observed.
Guidance devices of the type being discussed are suitable not only for laser cutting installations, but basically also for laser welding installation as well as installations in which material removal at workpiece surfaces is performed with the help of a laser beam, for instance for engraving or such like. Other areas of utilization are hardening, remelting and surface alloying. If in the following only laser cutting is discussed, the inventive device can, however, be utilized for all laser application cases, in which it is important to move laser head and workpiece precisely guided relative to each other.